MAXIM MAX2056 User Manual

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General Description

The MAX2056 evaluation kit (EV kit) simplifies evalua­tion of the MAX2056 general-purpose, high-perfor­mance, variable-gain amplifier with analog gain control.
The EV kit is fully assembled and tested at the factory.
Standard 50Ω SMA connectors are included at the
input and output of the EV kit to allow quick and easy
evaluation on the test bench.

This data sheet provides a list of equipment required to
evaluate the device, a straightforward test procedure to
verify functionality, a circuit schematic for the kit, a bill
of materials (BOM) for the kit, and artwork for each
layer of the PC board.

Features

♦ Analog Gain Control

♦ Up to 44dB Gain-Control Range

♦ 800MHz to 1000MHz Frequency Range

♦ Fully Assembled and Tested

♦ Input and Output Internally Matched to 50Ω Over

Entire Band Of Operation

♦ 50Ω SMA Inputs and Outputs for Easy Testing of

All MAX2056 Features

Evaluates: MAX2056

MAX2056 Evaluation Kit

________________________________________________________________ Maxim Integrated Products 1

19-3552; Rev 0; 2/05

Component List

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

Component Suppliers

PART TEMP RANGE IC PACKAGE

MAX2056EVKIT -40°C to +85°C

36 Thin QFN-EP*

*EP = Exposed paddle.

DESIGNATION

QTY

DESCRIPTION

C1, C3, C5,

C10

4

47pF ±5%, 50V C0G ceramic
capacitors (0402)
Murata GRP1555C1H470J

C2, C4, C6,

C8, C9

5

1000pF ±10%, 50V X7R ceramic
capacitors (0402)
Murata GRP155R71H102K

C7 1

3.9pF ±0.1pF, 50V C0G ceramic
capacitor (0402)
Murata GRP1555C1H3R9B

C11, C12, C16

0 Not installed (0603)

C13, C14, C15

3

0.1µF ±10%, 16V X7R ceramic
capacitors (0603)
Murata GRM188R71C104K

C17 0 Not installed (0402)

J1–J5 5

PC board edge-mount SMA RF
connectors (flat-tab launch)
Johnson 142-0741-856

R1 1 1.2kΩ ±1% resistor (0402)

SUPPLIER PHONE WEBSITE

Johnson 507-833-8822 www.johnsoncomponents.com

Murata 770-436-1300 www.murata.com

DESIGNATION QTY DESCRIPTION

R2 1 3.92kΩ ±1% resistor (0402)

R3, R4 2 0Ω resistors (0402)

Large test point for 0.062in PC

TP1 1

board (red)
Mouser 151-107 or equivalent

TP2 1

U1 1

Large test point for 0.062in PC
board (black)
Mouser 151-103 or equivalent

Analog VGA IC
(36-pin, 6mm x 6mm thin QFN-EP)
Maxim MAX2056ETX
NOTE: U1 HAS AN EXPOSED
PADDLE CONDUCTOR THAT
REQUIRES IT TO BE SOLDER
ATTACHED TO A GROUNDED PAD
ON THE PC BOARD TO ENSURE A
PROPER ELECTRICAL/THERMAL
DESIGN.

Evaluates: MAX2056

Quick Start

The MAX2056 EV kit is fully assembled and factory tested.
Follow the instructions in the Connections and Setup
section for proper device evaluation.

Test Equipment

• One DC power supply capable of supplying 5V
and 0.3A

• One DC power supply that can be adjusted from 1V
to 4.5V for gain control

• Two digital multimeters (DMM) to monitor V

CC

and

ICC, if desired

• HP 8648 (or equivalent) signal source

• HP 8561E (or equivalent) spectrum analyzer

• HP 8753D (or equivalent) network analyzer to mea­sure return loss and gain over frequency (optional)

Connections and Setup

This section provides a step-by-step guide to testing
the basic functionality of the EV kit. To prevent damag­ing the device, do not turn on DC power or RF signal

generators until all connections are made. Do not
apply VCNTL without VCCpresent (see the VCNTL
section).

Testing the Supply Current

1) Connect 50Ω terminations to J1 and J2.

2) With its output disabled, set the voltage on one of
the DC supplies to +5.0V (through a low internal
resistance ammeter, if desired) and connect to the
+5.0V (TP1) and GND (TP2) terminals on the EV kit.
If the power supply has a current-limiting feature,
set the current limit to 200mA.

3) With its output disabled, set the voltage on the sec­ond DC supply to 1V and connect to the gain-control
connector VCNTL (J3) on the EV kit. This configures
the device for its maximum gain setting. If the power
supply has a current-limiting feature, set the current
limit to 1mA.

4) Enable the VCCsupply, then enable the gain-control
supply; the VCCsupply current should read approxi­mately 136mA.

Testing the Power Gain

1) With its supply output disabled, set the voltage on one
of the DC supplies to +5.0V (through a low internal
resistance ammeter, if desired) and connect to the
+5.0V (TP1) and GND (TP2) terminals on the EV kit. If
available, set the current limit to 200mA.

2) With its supply output disabled, set the voltage on the
other DC supply to 1V and connect to the gain-control
connector VCNTL (J3) on the EV kit. If available, set
the current limit to 1mA.

3) With the generator output disabled, connect the RF
signal generator to J1. Set the generator to a
900MHz output frequency, and set the power level
to -13dBm.

4) Connect the spectrum analyzer to J2. Set the spec­trum analyzer to a center frequency of 900MHz and
a total span of 1MHz. Set the reference level on the
spectrum analyzer to +10dBm.

5) Enable the V

CC

supply. Next, enable the gain-control
supply. Finally, enable the RF generator’s output. A
900MHz signal with a magnitude of approximately
3dBm should be displayed on the spectrum analyzer.
Be sure to account for external cable losses.

6) Vary the gain-control supply voltage between +1.0V
and +4.5V. The output power should vary by
approximately 22dB.

7) Gain can also be determined with a network analyzer.
This has the advantage of displaying gain over a
swept frequency band, in addition to displaying
input and output return loss. Refer to the network
analyzer manufacturer’s user manual for setup
details (optional).

Detailed Description

Figure 1 shows the schematic for the MAX2056 EV kit.
C1, C3, C5, and C7 are DC-blocking capacitors for the
IN_A, IN, AMP_IN, and OUT pins. To reduce the possi­bility of noise pickup from the power supply, capacitors
C2, C4, C6, C8, C9, C10, C13, C14, and C15 are used
to decouple VCC. Resistors R1 and R2 are used to bias
the amplifier’s first and second stages, respectively.

Current-Setting Resistors

The MAX2056 amplifier section is a two-stage design
whose input stage current is set by the external resistor
R1, while the output stage current is set by resistor R2.
These resistors were optimized at the factory to pro­duce the highest OIP3 for a given current. The current
of the device can be reduced by increasing these
resistor values (see the Modifying the EV Kit section),
but linearity performance degrades.

MAX2056 Evaluation Kit

2 _______________________________________________________________________________________

VCNTL

The VCNTL pin is used to control the gain of the amplifi­er. The nominal operating range for the VCNTL pin is
from 1V to 4.5V. Limiting VCNTL to this range ensures
reliability of the device. Due to on-chip ESD diodes, do
not apply VCNTL without V

CC

(+5V) present. If this con­dition is unavoidable, then change R4 on the EV kit to a
resistor no smaller than 200Ω. This resistor will limit the
current into the VCNTL pin for cases where VCCis
grounded or left open.

Modifying the EV Kit

Increasing the value of the external current-setting
resistors, R1 (first amp stage) and R2 (second amp
stage), can reduce the current draw of the amplifier
section of the device. Doubling the values of each of
these external resistors cuts the DC current drain
approximately in half but at the expense of approxi­mately 5.4dB lower OIP3. Since the linearity of the
amplifier is set by the cascaded performance of the two
amplifier stages, one must be careful to balance the
current distribution of the two stages to optimize OIP3
at the lowest current.

The MAX2056 EV kit has been designed and assembled
to add the flexibility of measuring the device in different
configurations. The kit has been assembled to cascade
one attenuator section followed by the output amplifier.
Some other configurations can be set as follows.

Configuration A) To use two attenuators followed by an
output amplifier: Move capacitor C3 on the EV kit to con­nect pin 2 trace to pin 35 trace of the IC. Apply the RF
input signal to SMA J4 and take the output signal from
SMA J2.

Configuration B) To use only the attenuator between IC
pins 2 and 8: Move capacitor C3 to connect the pin 2
trace of the IC to the trace of connector J1. Apply the RF
input signal to SMA J4 and take the output signal from
SMA J1.

Configuration C) To use only the attenuator between IC
pins 35 and 29: Move capacitor C5 to connect the pin 29
trace of the IC to the trace of connector J5. Apply the RF
input signal to SMA J1 and take the output signal from
SMA J5.

Configuration D) To use only the amplifier: Move capaci­tor C5 to connect the pin 26 trace of the IC to the trace of
connector J5. Apply the RF input signal to SMA J5 and
take the output signal from SMA J2.

Configuration E) To insert a function between one attenu­ator and an output amplifier, configure the board for both
configuration B and D. Insert the desired function
between SMA connectors J1 and J5. Apply the input sig­nal to SMA J4 and take the output signal from SMA J2.

Layout Considerations

The MAX2056 evaluation boards can be used as a
guide for board layout. Pay close attention to thermal
design and placement of components on the PC board.
The exposed paddle (EP) on the MAX2056 package
conducts heat away from the die and provides a low­impedance electrical connection. The EP must be
attached to the PC board ground plane with a low ther­mal and electrical impedance contact. Ideally, this is
provided by soldering the backside package contact
directly to a metal ground plane on the PC board.
Alternatively, the EP can be connected to a ground
plane using an array of plated vias directly below the
EP. The MAX2056 EV kit uses nine evenly spaced,

0.016in-diameter, plated through holes to connect the
EP to the lower ground planes.

Evaluates: MAX2056

MAX2056 Evaluation Kit

_______________________________________________________________________________________ 3

Evaluates: MAX2056

MAX2056 Evaluation Kit

4 _______________________________________________________________________________________

36 35 34 33 32 31 30 29 28

10 11 12 13 14 15 16 17 18

1

2

3

4

5

6

7

8

9

27

26

25

24

23

22

21

20

19

GND IN GND GND V

CC

GND GND ATTN_OUT GND

MAX2056

U1

EXPOSED

PADDLE

GND V

CNTL

GND V

CC

GND R

SET1

V

CC

R

SET2

GND

GND

AMP_IN

V

CC

GND

GND

GND

GND

OUT

GND

GND

OUT_A

GND

GND

V

CC

GND

GND

IN_A

GND

C3*

47pF

J1

RF_IN

C3*
47pF

C5*
47pF

C4
1000pF

C12
OPEN

+5V

J5

C6
1000pF

C13

0.1µF

+5V

C11

OPENC21000pF

+5V

C1

47pF

C7

3.9pF

C17
OPEN

R1

1.2kΩ

R2

3.92kΩ

C8
1000pF

C14

0.1µF

+5V

C9
1000pF

C15

0.1µF

R3

0Ω

+5V

TP1TP2

GND

C10
47pF

C16
OPEN

R4

0Ω

J3

VCNTL

*SEE THE MODIFYING THE EV KIT SECTION
FOR CONNECTION CONFIGURATIONS.

J4 J2

RF_OUT

C5*

47pF

C5*

47pF

Figure 1. MAX2056 EV Kit Schematic

Evaluates: MAX2056

MAX2056 Evaluation Kit

_______________________________________________________________________________________ 5

Figure 2. MAX2056 EV Kit PC Board Layout—Top Silkscreen

1.0"

Figure 3. MAX2056 EV Kit PC Board Layout—Top Soldermask

1.0"

Figure 4. MAX2056 EV Kit PC Board Layout—Top Layer Metal

1.0"

Figure 5. MAX2056 EV Kit PC Board Layout—Inner Layer 2 (GND)

1.0"

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

6 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.

Evaluates: MAX2056

MAX2056 Evaluation Kit

Figure 6. MAX2056 EV Kit PC Board Layout—Inner Layer 3
(Routing)

1.0"

Figure 7. MAX2056 EV Kit PC Board Layout—Bottom Layer
Metal

1.0"

Figure 8. MAX2056 EV Kit PC Board Layout—Bottom Soldermask

1.0"

Figure 9. MAX2056 EV Kit PC Board Layout—Bottom Silkscreen

1.0"